<div class="change-child">
  <h3>这是child组件</h3>
  <p>childName: {{ childName }}</p>
  <p>武器: {{ arms }}</p>
  <button class="btn btn-danger" (click)="position = '上'">改变位置</button>
  <app-change-grandson [position]="position"></app-change-grandson>
</div>
